Around 1,200 people were evacuated from one of London's most popular West End musicals after a small fire in the boiler room of the theatre, London Fire Brigade (LFB) said.

The cast, who were performing a matinee of Les Miserables at the Queen's Theatre in Shaftesbury Avenue, are also believed to have been ousted from the theatre along with the audience as a precaution.

Following new information, a spokeswoman for LFB said: "There was a small fire caused by a failing high voltage joint in what we understand was the boiler room.

"It was declared safe by the UK Power Network and the two fire crews have now left the scene.

" Around 1,200 persons had already been evacuated as a precaution before the arrival of the crews.

"There were no injuries or serious fire."

The neighbouring Gielgud Theatre, home to the Curious Incident Of The Dog In The Night-Time, is believed to have experienced a power cut as a result of the incident.

Audience members said on Twitter that they experienced a black-out half-way through the show.

Grace Perry tweeted: "Half way through watching a play and the whole of Shaftesbury avenue decides to have a powercut. Brill"

She added that after being evacuated the Les Miserables cast, who were still in costume, were helping by "just wondering round giving people directions".

Fire crews were called shortly before 3pm and left the scene around 4.30pm.

The London production of Les Miserables is the world's longest running musical where it played 7,602 performances at the Palace Theatre before transferring to the Queen's Theatre where it opened in April 2004, according to the show's website.

This year it will celebrate its 30th anniversary in London.

The Curious Incident Of The Dog In The Night-Time recently moved to the Gielgud Theatre following the collapse of part of the Apollo Theatre during a performance in December 2013, which left 88 people injured.

A spokesman for the Queen's Theatre said the stage blackout had been caused by an overheated cable.

The problem has been fixed and the show will go on with tonight's evening performance going ahead as planned.

He said: "Today's matinee of Les Miserables had to be cancelled after the theatre was evacuated 30 minutes into the performance due to the overheating of a cable supplied by UK Power Network to a transformer under the theatre which caused a blackout on stage.

"Whilst the auditorium was not affected, the audience, cast, orchestra and crew were asked to leave the building by precaution.

"The Fire Brigade attended to ensure that the theatre was safe to be re-entered and UK Power Network came on site to resolve the problem.

"Audience members affected by the cancellation of the matinee are invited to request a full refund at their original point of purchase.

"We are sorry for the inconvenience and disappointment caused and look forward to welcoming patrons to another performance of Les Miserables."